1. Field
The presently disclosed subject matter relates to devices, systems, and processes useful for executing a drive ratio changeover and reducing rollback in a vehicle, particularly, reducing rollback when a vehicle transfers from a high to a low range.
2. Description of the Related Art
Drive ratio changeover can occur during circumstances when a vehicle would run more efficiently at a lower or higher drive range ratio. These drive ratio changeovers can be executed manually by a vehicle operator. Often a drive ratio changeover will be necessary during ascent of an inclined road, and often times can occur when the vehicle is towing cargo. As the need for drive force increases, a changeover from a high range drive ratio to a low range drive ratio is often beneficial. However, conventionally, during this changeover the vehicle tends to momentarily slip or roll backwards commensurate with the slope of the roadway or other vehicle operating conditions.
Vehicle rollback during drive range changeover is generally undesirable as it can affect the driver who may momentarily feel a loss of control over the vehicle. Additionally, rollback can be particularly undesirable in situations where a heavy load is being towed by the vehicle or, for example, the vehicle is climbing a boat ramp. The following disclosure provides a system and control method for executing a drive ratio changeover when ascending a steep slope without rollback.